/Engine/Source/Runtime/Engine/Classes/EdGraph/EdGraphSchema.h
Categorizes two pins into an input pin and an output pin. Returns true if successful or false if they don't make sense as such (two inputs or two outputs)
template<typename PinType> static bool CategorizePinsByDirection ( PinType * PinA, PinType * PinB, PinType *& InputPin, PinType *& OutputPin )